Research news

There is an increasing demand for high-performance functional devices with liquid crystals to control and modulate THz waves. In such cases, liquid crystal devices employing external magnetic field to control optical effects are preferred as they do not require ITO electrodes which are polarization selective. Ji et al. report the optical and magneto-optical properties of mixtures of liquid crystals having ferromagnetic nanoparticles in the THz regime. Particularly, magnetically induced birefringence characteristics of the composite systems for THz liquid crystal phase shifter are discussed. A phase shift range between ne and no, by changing the magnitude of the external magnetic field without changing its direction has been achieved. The interaction between magnetic cluster chains formed by the ferroparticles, with the liquid crystal director and the external magnetic field, is explained theoretically by comparing the surface anchoring force and the magnetic moment in the dynamic system.